The basic components of an overrunning roller clutch include a cage, a plurality of cylindrical rollers, and a matching plurality of roller energizing springs. Roller clutches, especially those installed in an assembly line process, generally experience a fair amount of shaking during shipping and handling, before they are installed between a cam race and a pathway race. It is important that the components be retained together as a unit during shipping, for ease of handling and installation. Shipping retention is most difficult for the rollers, since they are heavy, cylindrical and smooth, and since any shipping retention structure must not be allowed to hinder the circumferential travel of the roller between the races after installation.
The conventional approach is to rely on the resilience of the springs to press the rollers against roller rest su faces on the cage prior to installation. This requires no change in the basic shape of the spring or cage, since the front leaves of the springs generally are curved to conform to the rollers anyway, and a cross bar or other part of the cage can easily be modified to provide a roller conforming rest surface. Nor is there any impingement upon the ability of the roller to travel, since installation is generally done by a pushing and simultaneous twisting action of the pathway race, called "ringing in." All of the rollers are shifted away from the roller rest surfaces of the cage, compressing the springs at the same time. The rollers never again touch the roller rest surfaces of the cage after clutch installation. The great problem with the old approach is that it is not particularly positive or secure. The energizing springs are not highly resilient, nor should they be, and so they cannot hold the rollers with a great deal of security. The rollers can easily be shaken loose, and such clutches have to be carefully handled.
An alternative roller shipping retention scheme which is not totally independent of the energizing springs, but is at least independent of the resilience of the energizing springs, is shown in U.S. Pat. No. 3,942,616 to Elmore. Axially opposed pairs of tabs are lanced inwardly from the metal side rails of the cage, and extend into hollowed out ends of the rollers. The tabs are used as the energizing springs for the rollers, and to retain the rollers to the clutch. While the rollers are retained securely, roller travel is severely limited, to less than the diameter of the rollers at most. Furthermore, the short tabs cannot provide enough resilience to allow the rollers to travel over a path even as large as the diameter of the depression in the end of the roller. Consequently, a densely packed complement of short traveling is necessary, which is impractical for most applications.
Another roller shipping retention scheme that is independent of the resilience of the spring, but which does not adversely affect roller travel, is disclosed in U.S. Pat. No. 4,724,940 to Lederman, assigned to the assignee of the current invention. Specially designed springs with latch portions are securely interfitted with latch members on the cage to trap the rollers against roller rest surfaces on the cage prior to clutch installation. The roller shifting action of the ringing in installation method is used to release the latch members, and the rollers and springs perform without restriction thereafter. The springs are not conventional, however, and a certain amount of give must be built into either the cage side rails, the springs, or both, to allow for latch disengagement during installation.
Recent advances in roller clutch design by the assignee of the subject invention have provided yet another roller shipping retention scheme, one that is totally independent of the spring in every sense, but which is dependent on the roller shifting action of the ringing in installation method. A roller control car contains each roller, sliding back and forth between the cage side rails with the roller as the roller travels. Before installation, a releasable latch securely holds the car and its roller to the cage in a shipping position removed from the eventual position of the car and roller after installation. During ringing in, the shift of the rollers shifts the cars as well, and releases the latches, freeing the rollers and their cars for unhindered travel. How strongly the roller is retained to the cage during shipping depends only on the strength of the latch, and the spring need not even be present during shipping. While the roller car with latch provides a very secure retention, assembly does require that each car latch member be pop fitted into its respective cage latch member with a fair degree of precision, to assure thorough and complete latching. Furthermore, during the ringing in of the pathway race, the simultaneous, or near simultaneous, disengagement of a plurality of strongly engaged latching members inevitably requires some extra torque, and can disturb the smoothness of the installation operation, not in terms of final result, but in terms of sound and feel.